Locking mechanism for a foldable piece of seating furniture

ABSTRACT

The present device is a locking mechanism for a piece of seating furniture that is continuously foldable, comprising a cylindrical bushing (3), which is fixed to the frame of the piece of seating furniture and which is provided with a pair of diagonally arranged holes (4) for an upwards inclined carrier bar (6), which is fixed to the seat part, and comprising a locking member (7) jointly operative with the carrier bar (6) as well as a control member (8) acting upon the locking member (7). The device is characterized in that the holes (4) are, at least in the peripheral direction, considerably larger than the cross section of the carrier bar (6), that inside the bushing (3) an inner bushing (12) is fitted freely turnably, the bushing (12) being provided with diagonally placed holes (13) for the carrier bar (6) and having a closed end (14), that the locking member (7) is spring-loaded and provided with a through hole (15) for the carrier bar (6) and pivotally mounted in the inner bushing (12), the locking member (7), when in the normal position, locking the movement of the carrier bar (6) in the direction of the spring force.

FIELD OF THE INVENTION

The present invention concerns a locking mechanism for a piece ofseating furniture that is continuously foldable, comprising acylindrical bushing, which is fixed to the frame of the piece of seatingfurniture, preferably to its arm part, and which is provided with a pairof diagonally arranged holes for an upwards inclined carrier bar, whichis fixed to the seat part of the piece of seating furniture and whichforms an acute angle open towards the front of the piece of seatingfurniture with the main plane of the seat part, and comprising a lockingmember jointly operative with the carrier bar as well as a controlmember acting upon the locking member.

BACKGROUND OF THE INVENTION

Prior-art locking mechanisms of this type are usually operated by meansof a control screw, by whose means the mobility and thereby thefoldability of a piece of seating furniture can be locked and graduallyreleased. It is a drawback of this prior-art type of locking mechanismthat from the lowered rest position the piece of seating furniturecannot be brought back to the normal sitting position without firstreleasing the locking mechanism, i.e. screwing on the control handle.When the piece of seating furniture is in the rest position, rising fromthis is quite difficult, because its seat part has then been pushedforward and is in a markedly raised position, at the same time as theback part has been lowered strongly rearwards.

SUMMARY AND OBJECTS OF THE INVENTION

The object of the present invention is to eliminate the above drawbacks,which is achieved by means of a locking mechanism which is characterizedin that the diagonally arranged holes are, at least in the peripheraldirection, considerably larger than the cross section of the carrierbar, that inside the first bushing a second, inner bushing, preferablymade of plastic, is fitted freely turnably, that the inner bushing isprovided with diagonally placed holes which are fitted tightly aroundthe carrier bar and is provided with a closed end against the arm part,that the locking member, which comprises a plane metal piece with acentral through hole or cavity for the carrier bar, is arranged insidethe inner mobile bushing with one of its ends pivotally mounted in themantle of said bushing and is spring-loaded in the direction towards thefront of the piece of seating furniture for locking of the movement ofthe carrier bar in this direction, and that the control member ismounted in an end wall of the inner bushing in a position next to thefront side of the free end of the locking member, being arranged topress the free end of the locking member rearwards by the effect of anexternal force, whereby the carrier bar is made free.

By means of the solution in accordance with the present invention, alocking mechanism is obtained which permits shifting of the carrier barrearwards irrespective of the position of the control member, wherebythe seat part and the back part of the piece of seating furniture arebrought to the normal sitting position, but for continuous lowering tothe desired rest position it is required that the locking member of thelocking mechanism is first released by means of easy operation of thecontrol member.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following, the invention will be described in more detail withreference to the accompanying drawing, wherein

FIG. 1 is a side view of an exemplifying embodiment of a lockingmechanism in accordance with the invention,

FIG. 2 is a sectional view of the locking mechanism taken along the lineA--A in FIG. 1,

FIG. 3 shows an exemplifying embodiment of a piece of seating furnitureprovided with a locking mechanism in accordance with the invention, thepiece of seating furniture being shown in the normal sitting position aswell as in a lowered rest position.

The locking mechanism in accordance with the invention comprises acylindrical bushing 3, which is fixed to the frame 1 of the piece ofseating furniture, preferably to its arm part 2, and which is providedwith a pair of diagonally arranged holes 4 for an upwards inclinedcarrier bar 6, which is fixed to the seat part 5 of the piece of seatingfurniture and which forms an acute angle open towards the front of thepiece of seating furniture with the main plane of the seat part 5, ascomes out from FIG. 3, a locking member 7 jointly operative with thecarrier bar 6, as well as a control member 8 acting upon the lockingmember 7.

The foldability of the piece of seating furniture is achieved therebythat its back part 9 is pivotally attached to the rear upper portions ofboth of the arm parts 2 by means of axle journals 10, at a distance fromthe lower end of the back part 9, which is attached pivotally by meansof axle journals 11 to the rear portion of the seat part 5. The seatpart 5 is supported by means of a pair of carrier bars 6, each of whichis slidably mounted in a bushing 3 of its own, fixed to thecorresponding arm part 2. At the front ends, the carrier bars 6 arepreferably bent down to permit fixing of their both ends to the frame ofthe seat part 5. In order to permit arc-formed movement of the seat part5 during folding movement of the piece of seating furniture, the holes 4made diagonally into the bushing 3 are, at least in the peripheraldirection, considerably larger than the cross section of the carrier bar6, while a second, inner bushing 12, preferably made of plastic, isfitted freely turnably inside the first bushing 3. This inner bushing 12is likewise provided with diagonally made holes 13, which are, on thecontrary, fitted closely around the carrier bar 6. Moreover, the innerbushing 12 is provided with a closed end 14 against the arm part 2. Thelocking member 7, which comprises a plane metal piece with a centralthrough hole 15 or cavity for the carrier bar 6, is arranged inside theinner mobile bushing 12 with one of its ends pivotally mounted in themantle of said bushing 12 and is spring-loaded in the direction towardsthe front of the piece of seating furniture, e.g., by means of a spiralspring 16 fitted around the carrier bar 6 and acting between the innerbushing 12 and the locking member 7. By means of the spring force, thefree end of the locking member 7 is pressed to such an extent forwardsthat the movement of the carrier bar in the direction forwards is fullyexcluded, which has the result that unintentional lowering of the pieceof seating furniture to a rest position is impossible. On the contrary,the locking mechanism permits unhindered shifting of the locking bar 6rearwards without acting upon the control member when one attempts torise from the rest position off the chair. Hereby, when the rear part ofthe seat part 5 is pressed down and somewhat rearwards in a natural way,the back part 9 rises and the seat part 5 is shifted rearwards fullyautomatically to the normal sitting position. The control member 8 ismounted in an end wall 14 of the inner bushing 12 in a position next tothe front side of the free end of the locking member. The control member8 is arranged to press the free end of the locking member 7 by theeffect of an external force to such an extent rearwards that the carrierbar 6 is made free, whereby it is freely mobile in both directions.Thus, when the control member 8 is acted upon from outside, continuouslowering of the piece of seating furniture to the desired rest positionis permitted. As soon as the effect on the control member 8 isdiscontinued, the carrier bar 6 is locked and the piece of seatingfurniture is fixed in the rest position that was chosen.

The control member 8 is mounted preferably turnably in the end wall 14of the inner bushing 12 and comprises a rod axially aligned with thebushing 12 and having a substantially crescent-shaped section along theportion 8a that reaches contact with the locking member 7, as comes outclearly from FIGS. 1 and 2. In the normal position, when the movement ofthe carrier bar 6 forwards is locked, the substantially plane portion ofthe control member 8 is placed facing towards the locking member 7. Whenthe piece of seating furniture is supposed to be lowered to a restposition, the control member 8 is turned somewhat so that the free upperend of the locking member 7 is shifted rearwards to such an extent thatthe carrier bar 6 is made free, which takes place when the lockingmember 7 becomes positioned exactly perpendicularly to the carrier bar.

In order to guarantee a smooth operation of the locking mechanism, theinner bushing 12 may be advantageously provided with an axially directedsupport 17 for the control member 8 along the inner mantle face of thebushing. The support 17 is appropriately shaped as having a concaveglide face for the control member 8.

With the solution in accordance with the present invention, it is simpleto pass the control member 8 from one side of the arm part 2 to theother side by passing it into the arm part 2 making a hole or anarc-shaped slot that permits the movement in the lateral direction thatis performed by the inner bushing 12 when the piece of seating furnitureis lowered from the normal sitting position to the lowest rest position.

Owing to the possibility of in this way placing the outer end of thecontrol member 8 on the outer side of the arm part 2, a control handle18 of the locking mechanism can be arranged easily in an easilyaccessible location at the arm 19 of the piece of seating furniturewithout having to restrict the space between the arms 2.

In its simplest embodiment the control handle 18 may consist of a handleor equivalent fitted at the outer end of the control member 8, but aneven more comfortable operation is obtained, e.g., if the control handle18 is placed right below the front end of the arm 19 in the form of aflap which can be pressed upwards, which is arranged to act upon thecontrol member 8 by the intermediate of a flexible cable 21 or aconnecting rod 23.

In order to convert the movement of the control handle 18 to a movementof rotation of the control member 8 itself, the outer end of the lattermay be advantageously provided with an eccentric disk, 22 which is, bythe intermediate of a connecting rod, 23 arranged to be acted upon by acontrol handle 18 fitted on the bottom side of the arm rest 19.

If the piece of seating furniture is a chair, as is shown in FIG. 3,only one locking mechanism with related control handle 18 is required,while the other side of the seat part 5 is supported, e.g., by a freelymobile carrier bar 6 that is passed through a fixed outer bushing 3 anda mobile inner bushing 12. On the contrary, when the piece of seatingfurniture consists of a sofa, it is required that the piece of seatingfurniture is provided with control handles 18 at both of the arms 19,said control handles 18 being connected, by means of flexible cables oftheir own, to the outer end of the control member 8 of the lockingmechanism, e.g., by the intermediate of an eccentric cam or equivalent.If the sofa is of a wider type or if its back part 9 is not sufficientlyrigid, it may be advisable to provide both sides with a lockingmechanism, said locking mechanisms being affected jointly by both of thecontrol handles 18 via flexible cables.

In order to ensure constant free mobility of the carrier bars 6 in therearward direction, the locking member 7 is appropriately mounted to theinner bushing 12 with a little play, whereby an elastic tongue 20 isfitted to push the fixed end of the locking member 7 in the forwarddirection, whereby unintentional jamming is counteracted.

What is claimed is:
 1. Locking mechanism for a readjustable chaircomprising: a cylindrical bushing fixed to a frame of the chair andprovided with a pair of diagonally arranged holes for an upwardsinclined carrier bar fixed to a seat part of the chair and forming anacute angle with a main plane of said seat part and rising towards afront of the chair; said holes being considerably larger than a crosssection of said carrying bar in a peripheral direction; an inner bushingturnably mounted inside said cylindrical bushing; said inner bushingbeing provided with diagonally placed holes tightly fitting around thecarrier bar, said inner bushing being provided with a closed end wallagainst the frame of the chair; a locking member mounted inside saidinner bushing jointly operative with said carrier bar and comprising aplane metal piece provided with a central through hole, said carrier barextending through said central through hole, said locking member havinga free end and an end pivotally mounted in a mantle of said innerbushing and being spring-loaded in a direction towards the front of thechair, locking the movement of the carrier bar in this direction; acontrol member acting upon said locking member, said control memberbeing mounted in said closed end wall of said inner bushing in aposition next to a front side of said free end of said locking member,said control member being arranged to press said free end of saidlocking member rearwards by effect of an external force, whereby saidcarrier bar is made free for movement relative to said cylindricalbushing.
 2. Locking mechanism according to claim 1, wherein said innerbushing is formed of plastic.
 3. Locking mechanism according to claim 1,wherein said control member is mounted turnably in said end wall of theinner bushing and comprising a rod axially aligned with the bushing andhaving a substantially crescent-shaped section along a portion being incontact with said locking member, a plane face of said portion beingfaced toward the locking member in a normal position of said controlmember.
 4. Locking mechanism according to claim 3, wherein said innerbushing is provided with an axially directed support for said controlmember, said support passing along an inner face of said inner brushing.5. Locking mechanism according to claim 4, wherein said cylindricalbushing is fixed to an arm part of said frame, said control member ispassed through a hole or slot in said arm part to another side of saidarm part.
 6. Locking mechanism according to claim 5, wherein an outerend of said control member is provided with a handle.
 7. Lockingmechanism according to claim 5, wherein an outer end of said controlmember is connected to an easily accessible control handle by means of aflexible cable or a connecting rod.
 8. Locking mechanism according toclaim 1 or 3 or 4 or 5 or 6 or 7 wherein said locking member endpivotally mounted in a mantle of said inner bushing is acted on by anelastic tongue acting in a direction of the spring force.
 9. A lockingmechanism for an adjustable chair, comprising:a cylindrical bushingfixed to a frame of the chair, said cylindrical bushing including a pairof diagonally arranged holes receiving an upwardly inclined carrier bar,said carrier bar being fixed to a seat part of said chair and forming anacute angle with a plane of said seat part, said carrier bar risingupwardly toward a front said chair, said pair of diagonally arrangedholes each having a peripheral dimension which is larger than a largestcross sectional dimension of said carrier bar; an inner bushing turnablymounted inside said cylindrical bushing, said inner bushing including apair of diagonally positioned holes tightly fitting around said carrierbar, said inner bushing having a closed end wall against the frame ofthe chair; a locking member positioned inside said inner bushing, saidlocking member having a through hole with said carrier bar passingthrough said through hole, said locking member having a first endpivotally mounted in said inner bushing and having a second free end; aspring element positioned in said inner bushing biasing said lockingmember towards a front end of the chair, locking the movement of thecarrier bar in the direction toward the front of the chair; and controlmeans mounted in said closed end wall of said inner brushing adjacentsaid free end of said locking member for pressing said free end of saidlocking member in a direction opposite the front of the chair forfreeing said carrier bar with respect to said locking member formovement of said carrier bar relative to said cylindrical bushing.
 10. Alocking mechanism for an adjustable chair, comprising:a cylindricalbushing fixed to an arm part of the chair, said cylindrical bushingincluding a pair of diagonally arranged holes receiving an upwardlyinclined carrier bar, said carrier bar being fixed to a seat part ofsaid chair and forming an acute angle with a plane of said seat part,said carrier bar rising upwardly toward a front of said chair, said pairof diagonally arranged holes each having a peripheral dimension which islarger than a largest cross sectional dimension of said carrier bar; aninner bushing formed of plastic, said inner bushing being turnablymounted inside said cylindrical bushing, said inner bushing including apair of diagonally positioned inner bearing holes tightly fitting aroundsaid carrier bar for sliding movement of said carrier bar within saidinner bearing holes, said inner bushing having a closed end wall againstthe frame of the chair; a locking member formed of a plane metal piecewith a central hole, said carrier bar passing through said central hole,said locking member being positioned inside inner bushing, said lockingmember having a first end pivotally mounted in said inner bushing andhaving a second free end; a spring element positioned in said innerbushing biasing said locking member towards a front end of the chair,locking the movement of the carrier bar in the direction toward thefront of the chair; and control means mounted in said closed end wall ofsaid inner bushing adjacent said free end of said locking member forpressing said free end of said locking member in a direction oppositethe front of the chair for freeing said carrier bar with respect to saidlocking member for movement of said carrier bar relative to saidcylindrical bushing.